Geographic Range

The White Sturgeon is found on the Pacific slope of North America from the Aleutian Islands, AK to Baja, CA. It is anadromous fish, spending most of its life in sea near the shore and can be found in estuaries of large rivers. It migrates far inland in large rivers to spawn. (Kee, et. al. 1981; Boschung, 1985).

Habitat

Historically, white sturgeon spent their life in several habitats; streams, rivers, estuaries, and marine waters. They are anadromous fish but may spend much or all of their lives in fresh water if they cannot reach the sea (Hart 1973). White sturgeon historically occurred on the Pacific Coast, reproducing in at least three large river systems, including Sacramento-San Joaquin River in California, the Columbia River basin in the Pacific Northwest, and the Fraser River system in British Columbia (Fish and Wildlife Service, Interior, 1994). The building of dams along the rivers has impacted the populations of white sturgeons by creating landlocked populations and destroying spawning grounds.

White sturgeon are still distributed throughout the river systems of the Pacific northwest, but these populations are isolated and their migration is limited within the series of pools and lakes that make up these new dammed rivers (Pacific States Marine Fisheries Commission, 2000)

Physical Description

There are several distinguishing characteristics of the white sturgeon. Its body is elongate and cylindrical and can be large, with sizes as large as 3.8 to 6 meters and weights as high as 630 kg.

It has no scales but five rows of "scutes" along the body. There are 11-14 plates in front of the single dorsal fin, 38-48 plates from the head along the central caudal axis, and 9-12 from the head to the pelvic fins. Dorsal color is light gray while the ventral surface is white.

The mouth is ventral, moderate in size and directed downward. The white sturgeon has no teeth, instead using its 'vacuum cleaner' like mouth that is capable of siphoning up food. This fish is recognized by its short broad snout with four barbels closer to the tip of the snout than the mouth. (Hart, 1973; Pacific States Marine Fisheries Commission 1996).

Reproduction

The exact reproductive window for white sturgeon is not known, however for sturgeons in general the males reproduce for 10 to 20 years and females for 15 to 25 years. The size or age of maturity is variable, and spawning occurs when the physical environment permits vitellogenesis (egg development) and cues ovulation. Landlocked sturgeons have been observed to spawn during periods of peak river flow with high water velocities that disperse and prevent clumping of the eggs. White sturgeon are broadcast spawners because they release their eggs and sperm in fast water. Information from Fish and Wildlife Service (1994)

Behavior

White sturgeon are slow growing, late maturing, anadromous fish.

Adults spend most of their time in sea near the shore, but they have been found in depths of 30 meters. Adults move into large rivers in early spring and spawn by May or June. They can ascend far inland to spawn (Lee 1980). Landlocked fish also migrate. Tagging studies of Kootemai river white sturgeon revealed that in spring, the fish were observed to have moved upriver 16 to 114 river kilometers, and remained congregated in specific locations through the summer. The fish that were sedentary during the summer inhabited the deepest holes of the river (Fish and Wildlife Service 1994).

Communication and Perception

Food Habits

White Sturgeon have been described as opportunistic feeders, feeding on the bottom with their long snouts and using their barbels to detect food. When small they feed on clams, mussels, crayfish, worms, and fish eggs. At a larger size, they prey on fish such as smelt, anchovies, lamprey, shad and salmon.

Economic Importance for Humans: Positive

The size combined with the "characteristic quality of its flesh" makes it a valuable game fish in areas were it is not protected. Its roe can be used for caviar, and Columbia river roe production is "second only to the former Soviet Union" (Hart 1973; Pacific States Marine Fisheries Commission 1996).

Conservation Status

In 1994, the population of White Sturgeon located in the Kootenai river was granted endangered status. The population has been declining since the 1960's and there has been a complete lack of recruitment of breeding juveniles in the population since 1974. The decline corresponds to the opening of the Libby Dam in Montana and possibly from poor water quality and the effects of contaminants (Fish and Wildlife Service 1994).

Joint efforts between Canada and the United States are underway to address the needs of the Kootenai population by developing a regional recovery strategy (Duke, 2000).

Other Comments

White Sturgeons are the largest freshwater fish in North America. The largest white sturgeon was taken from the Snake River in Idaho in 1898 and it weighed 682 kilograms (Duke 2000).

The name comes from "acipenser," an Old World name meaning sturgeon and transmontantanus meaning beyond the mountains. This seems fitting for a fish found west in the New World (Pacific States Marine Fisheries Commission 1996).

Contributors

William Fink (editor), University of Michigan-Ann Arbor.

Charles Dershimer (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

tactile

uses touch to communicate

References

Boschung, H. 1985. The Audubon Society Field Guide to North American Fishes, Whales, and Dolphins. New York: AAlfred A. Knopf, Inc..

Fish and Wildlife Service, Interior, September 6, 1994. "Endangered and Threatened Wildlife and Plants; Determiniation of Endangered Status for the Kootenai River Population of the White Sturgeon" (On-line).
Accessed
October 22, 2000
at http://endangered.fws.gov/r/fr94549.html.

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.